Control system for tobacco hoppers



Aug. 9, 1960 E. w. DE VOTO ETAL Filed July 17, 1958 CONTROL. SYSTEM'FOR TOBACC O HOPPERS 3 Sheets-Sheet 1 ALBERT M GARm/v JOSEPH E HORNER EARL W DEVOT0 ATTORNEY Aug. 9, 1960 E. w. DE VOTO ETAL 2,943,281

CONTROL SYSTEM FOR TOBACCO HOPPERS 3 Sheets-Sheet 2 Filed July 17. 1958 M Y m m wmmo m T T G um s mp B E L L R 4 5 United States Patent O7 CONTROL SYSTEM FOR TOBACCO HOPPERS Earl W. De Voto, Albert M. Garton, and Joseph E. Homer, Richmond, Va., assignors to Philip Morris I Incorporated, New York, N.Y., a corporation of Virginia 7 Filed .Inly 17, 1958, Ser. No. 749,186

16 Claims. (Cl, 131-21) The present invention relates to cigarette-making machines and more particularly to control systems employed to maintain the weight of cigarettes produced by such machines constant over extended periods of operation of the apparatus.

. Although the control apparatus of the present invention is applicable to various types of cigarette-making machines, it is described as applied to a machine as exemplified by the machine disclosed in Molins et a1. Patent No. 2,704,079. In the cigarette-making machine described in the aforesaid patent, tobacco from a feed hopper is showered onto an endless moving belt or hopper tape where it forms a stream of tobacco which is passed under a large presser roll in order to produce initial compacting of the tobacco mass. The compacted tobacco stream is thereafter fed onto a travelling web of cigarette paper which is supported on a second endless belt or rod tape, the tobacco again being compressed by a small presser roll at the point at which it is'fed onto the paper. The tobacco and paper are then formed into a rod of tobacco by the various steps of rolling, pasting, folding and heating and passes thereafter 2 v by cigarette-making machines, the apparatus did not realize the full potential of this general type of control system. The displacement of the measuring apparatus from the apparatus controlled thereby introduces a mechanism exhibited a high inertia to change in its oper-. ating speed and therefore its speed of response was 7 quite slow.

through a cutter mechanism where the rod is cut into individual cigarette lengths. The cigarettes are then operated upon by two deflector devices which deflect the cigarettes into two separate rows from which an operator may take them and place them into storage bins.

Until relatively recently, the weight of the cigarettes produced by the aforesaid cigarette-making machine was controlled by the operator through the medium of a control shaft that operates upon an expanding pulley device to control the speed of a shaft driving the hopper. When a machine was initially put into operation and at periodic intervals thereafter, batches of the cigarettes were weighed and if their weight deviations were beyond predetermined tolerances, the control shaft was manipulated to an extent deemed necessary to correct for such weight deviations.

In recent years, automatic control of cigarette-making machines has been undertaken, by employing devices for measuring the density of the tobacco rod prior to cutting or immediately thereafter, and controlling the aforesaid shaft in accordance with detected weight deviations. Various density measuring techniques have been employed, the more common of which have employed capacitive gauges and beta-ray gauges.

The gauge unit employed, whether it be a capacitive or beta-ray gauge produces an electric signal indicative of the density of the tobacco examined thereby. The electrical output signals produced by the detector were employed to operate a motor connected to rotate the aforesaid control shaft in the proper direction to reduce deviations in the density of the mass of tobacco from a desired standard weight.

Although the device described above considerably re It has been found that the delay introduced into the apparatus of the aforesaid patent as a result of mechanical inertia and transportation lag is of the order of magnitude of one hundred cigarettes, that is, a devia: tion which affects the control mechanism does not pro-i duce an effect which is detected at the density detector. until after about one hundred cigarettes or cigarette lengths have proceeded through the detector.

It is an object of the present invention to provide an automatic control mechanism for cigarette-making machines wherein the time lag between detection of an error in weight of the cigarette and response of the mechanism is relatively short.

-It is another object of the invention to control the hopper of a cigarette-making machine such that the transportation lag between the apparatus controlled and the weight detecting mechanism is reduced below that of conventional machines andfurther wherein the mechanical inertial lag in response of the hopper control is reduced below that of conventionalcontrols.

It is another object of the present invention to provide an automatic control mechanism for cigarette-making machines wherein the interval between a detection of a weight deviation of the massof tobacco by the detec tor and the subsequent detection of the weight is cor rected-in response to measurements isof the order of magnitude of twenty-five cigarette lengths.

As previously indicated in conventional automatic control mechanisms for cigarette-making machines, the density of the tobacco applied to the cigarette rod forming mechanism is determined by the speed of rotation of the various elements of the tobacco hopper of the machine and that all of the various elements of the hopper are geared to a common input shaft so that the speed of all elements is slaved to the speed of the single input shaft. In the hopper mechanism of the type to which the mechanism of the present invention will be referred, although it is not intended to limit the invention to a specific hopper construction, tobacco is fed between a main drum and a top drum both of which carry carding pins. A blanket of tobacco is formed'thereby on the main drum and thereafter brought into contact with a picker roll and fed thereby to a high velocity winnower for eliminating stems. The tobacco proceeds from the winnower to a vibrating plate where it is conveyed to a front steel drum which conveys it to a tobacco reservoir subsisting between 'a vibrating collator plate and the surface of the front steeldrum. The tobacco issuing from the reservoir that is between the vibrating collator plate and the front steel drum, is

duced the deviation in weight of the cigarettes produced deflected by a pin roller to a second picker roller onto a moving hopper tape which conveys the tobacco to the cigarette rod forming mechanism.

In the prior art mechanism a drive pulley was driven via a variable speed cone pulley from a main source .of

Patented Aug. 9, 1960,

rotary power and the speed of the output of the cone 7 of the-output portion of thecone pulley was conveyed to a main drive pulley which. drove the aforesaid single input shaft through a suitable gearreduction' mechanism. All operating members of the hopper were slaved to this main input shaft and therefore. the inertia of the system was quite large.

In accordance with the present invention the aforesaid pin roller, or alternatively the second picker roller is disconnected from the remainder of the hopper and the speed of rotation of the selected member, either the pin roller or the second picker roller, is controlled in accordance with thedensity detected by the density measuring gauge. Specifically, a control impulse motor is controlled in accordance with the deviation of the density of tobacco from the desired value and the position of the impulse motor controls the output speed of a variable speed transmission, which receives input rotary power from any convenient machine member, such as the compressor section.

The selected pin or picker roll is driven through suitable gear reduction members from the output of the variable speed transmission and is the only part of the mechanism coupled to the output of this variable speed transmission. The control impulse motor also controls the speed of the remaining elements of the system by means of an electrical network which controls the speed of rotation of the output member of the main hopper variable drive and therefor of the remainder of the feeder elements. Specifically, the control impulse motor for controlling the speed of the selected roller also positions a potentiometer, connected to an electrical circuit, with a second potentiometer driven by a second control impulse motor for controlling the output speed of the main hopper variable drive. Upon a variation of the position of the first control impulse motor, an electrical signal is developed which changes the position of the second control impulse motor until the electrical circuit is rebalanced. The change of position of the second variable speed transmission changes speed of rotation of all remaining elements of the feeder since the picker roll or the pin roll, whichever is employed, is the only member disconnected from the original drive mechanism.

Two decided advantages are achieved by utilizing the control mechanism as outlined above, which advantages are reflected in a considerable gain in the number of cigarettes falling within predetermined weight tolerances. Specifically, the fact that the selected pin (or picker) roller speed is controlled, means that the control signal is applied to a member which is considerably closer to the detection instrument, that is considerably closer to the output of the feeder than is the main drum which has been the element previously controlled by the original control apparatus. In consequence, the transportation lag between the detection member and the control member is reduced and therefore an initial reduction in the system inertia of the machine is achieved. Secondly, the fact that the control is applied directly to a single roll member and the fact that the remainder of the system is slaved to this member by an electrical rather than a mechanical connection effects a considerable reduction in the inertia of the system and therefore materially increases the speed of response to a change in the weight of the tobacco being fed to the rod forming apparatus.

It is essential to the operation of the system that the low inertia element draw tobacco from a tobacco reservoir rather than directly from the high inertia elements since it is apparent that the differences in speed of response of the low and high inertia elements is such that either too much or too little tobacco would be supplied to the low inertia element upon a decrease or increase respectively of its speed during that interval which represents the difierence in response times of the high and low inertia elements to a call for a change in speed. Not only must a reservoir be employed between the high and low inertia elements but the capacity of the reservoir must be such that the quantity of tobacco therein is maintained within predetermined limits during the aforesaid interval required for the high inertia elements to attain a. feed rate equal to the withdrawal rate of the low inertia mechanism upon a change in the withdrawal rate. The region of the apparatus employed as a reservoir in the apparatus of the invention is that region subsisting between the vibrating collator plate and the front steel drum which is a region of limited capacity. This region was chosen or more correctly either the pin roller or the picker roller was chosen as the low inertia member since there are no high inertia members that can affect the tobacco feed rate between the pin and second picker roller and the output chute of the hopper.

Since the reservoir employed has a relatively limited capacity the rate of change of the speed of the selected pin or picker roller must not be too great. In order't'o prevent too rapid a rate of change of speed of theselected roller, a considerable speed reduction ratio is effected between the output shaft of the impulse controlled variable speed drive and the driven selected roller shaft. This reduction being of the order of magnitude of fiftyto-one. In consequence of the utilization of this large gear reduction ratio, rapid changes in the high speed shaft of the speed reducer appear as considerably slower changes in speed of the selected pin or picker roller and therefore prevent exhaustion of the immediately preceding reservoir. v

The effectiveness of the control mechanism of the present control as compared to the effectiveness of the prior art control mechanism becomes apparent upon consideration of the relative percentages of acceptable cigarettes, that is, cigarettes falling within a predetermined minimum deviation. It has been found that the apparatus and control system of the present invention effects an increase in the number of acceptable cigarettes falling within a predetermined acceptable weight range of over 9% more than the percentage of acceptable cigarettes produced by the best of the machines controlled in accordance with the prior'art control systems.

It is therefore an object of the present invention to provide a variable speed drive for the selected pin roller or picker roller of the feeder of a cigarette rod making machine and to electrically control the speed of rotation of the remainder of the feeder elements in accordance with the speed of rotation of the selected pin or picker roller.

It is another object of the present invention to provide an automatic control system for cigarette-making machines in which a tobacco weight measuring instrument controls the speed of rotation of the selected pin roller or picker roller of the tobacco hopper feeding mechanism of such machines. V

The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of one specific embodiment thereof, especially when taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a cross-sectional view of a typical tobacco hopper feeding mechanism for cigarette-making machines;

Figure 2 is a perspective view of the drive mechanism for rotating the various elements illustrated in Figure l; and

Figure 3 is a schematic wiring diagram of the electrical system for controlling the speed of rotation of the feeder elements in accordance with the speed of rotation of the selected pin roller or picker roller.

Referring specifically to Figure 1, tobacco is fed onto an upwardly curved plate 1 at the left-side of the Fig- 'ure' 1 which corresponds to the rear of the first tobacco hopper generally designated. by the reference numeral 2. A filler. feed plate 3 which is disposed to the rear of the hopper and rearwardly of the tobacco; deposited on the plate 1 is periodically rotated counterclockwise by a reciprocating drive linkage 6. The filler feed plate 2 pushes the tobacco filler forward and up the curved surface of the plate 1 to a cleaner shaft 7 at intervals of about two minutes. The cleaner shaft 7 carries a plu-' rality of outwardly extending fingers 8 and the shaft 7 is rotated clockwise thereby conveying the filler to a second hopper generally designated by the referencenumeral 9. A plurality of downwardly depending forks 11, only one of which is illustrated may be adjusted rotatably about a shaft 12 from which they depend in order to provide a coarse control of the amount of filler fed through the gap between the cleaner shaft and the forks and into an intermediate portion of the hopper 9.

The tobacco fed forward by means of the cleaner shaft 7 drops onto a rear drum 13 which is secured to and rotates with a rotating shaft 14. The rear drum 13 carries a plurality of carding pins 16 and is rotated in the clockwise direction so as to convey the tobacco deposited thereon to a main drum 17 secured to and rotatable with a rotating shaft 18. The drum 17 also carries a plurality of carding pins 19 and is rotated in a clockwise direction. The tangled tobacco mass presented to the main drum 17 is picked up by the carding pins 19 while the shorts or the small bits of pieces of tobacco are not conveyed by means of the pins 19 and fall down the front of the rear drum into a rear chute 21. Also, some of the shorts are not conveyed by the rear drum 13 to the main drum 17 and drop down the rear of the rear drum also into the chute 21. The amount of tobacco carried forward, that is, toward the front of the hopper by the main drum 17 is determined by the adjustment of a plurality of rakes 22 which are adjustably positionable with respect to their distance from the main drum 17, on an oscillating shaft 23. Oscillation of the shaft 23 produces reciprocation of the rakes 22 and determines the quantity of tangled tobacco which passes between the rakes 22 and drum 17; that portion of the tobacco mass or filler which is intercepted by the rakes 22 is returned to the top of the rear drum 13. V

Rotation of the main drum 17 carries the filler to the top thereof where it is formed into a compacted roll by a tamper 24 which has a vertical reciprocating motion. The tamper is supported on a substantially vertical arm 26 which forms one side of a parallel arm arrangement designated by the reference numeral 27, a horizontal arm 28 of which is centralling pivoted about a shaft 29, and a parallel arm 28a pivoted about a shaft 30. The forward end 31 of arm 2% remote from the arm 26 is re ciprocated vertically, by an eccentric means as described later in order to impart vertical movement to the tamper 24 so that it pounds the tobacco against the main drum 17. The mass of tobacco compacted by the action of the tamper 24 passes between the main drum 17 and a top drum 32 secured to a rotatable shaft 33. The shaft 33 is rotated clockwise intermittently and is intended to prevent undue compacting and therefore binding of the mass of filler as it passes between the main drum and the top drum 32. The carding pins on the main drum 17 are longer than the plurality of carding pins 34 secured to the top drum '32 and therefore the main drum carries a blanket of the tobacco filler past the adjacent region of the top drum 32 and into the region of a comb section 36.

The comb section 36 comprises a plurality of downwardly depending flexible fingers 37 which are biased into contact with the tobacco on the main drum 17 due to their own resiliency. The comb restrains the filler and aligns it so that it may be picked off the drum 17 by a picker roll 38 which throws the tobacco into the path of a plurality of, typically four, rapidly rotating arms 39 of a winnower 41; the arms 39 being secured to and rotating with a shaft 42. The arms 39 of the winnower .41 strike the filler with considerable velocity and the trajectory of each particle so struck is determined by,

the density of that particle. As stems aremore densethan the normal tobacco filler, they are thrownupwardly into a stem box 43 while the remainder of the tobacco either falls onto a vibrating plate '44 or strikes a front wall 460i the stem box and drops backs onto a front steeldrum 47 supported on a rotatable shaft 45. That portion of the tobacco which falls onto the vibrating plate 44, whichv is vibrated by means of a reciprocating rod 48, is conveyed by the vibratingplate to the. front steel drum 47.7 The'front steel drum 47 rotates clockwise and carries the filler to a region located between the front steel drum. and a vibrating correlator plate 49 which is vibrated by means of an electromagnet 51. The tobacco which proceeds through the region between the correlator plate 49 and the steel drum 47 is pulled out of this region by means of a pin roller 52 secured to and rotatable with a rotating shaft 53.

The region between the correlator plate 49 and the steel drum 47 provides a reservoir of tobacco for the pin roller 52 in that the rate at which the tobacco proceeds through this region is determined to a considerable extent by the rate at which the pin roller 52 withdraws tobacco from the region. In vibrating conveyors the rate at which material is conveyed is dependentrupon the resistance to movement of the material so that in the present apparatus the quantity of tobacco supplied to the pin roller 52 per unit of time is determined by the speed of rotation of the roller within the limits of the storage capacity of the region between the correlator plate and front steel drum. The pin roller 52 is provided with a plurality of pins 54 arranged about its circumference and these pins are adapted to engage the tobacco emitted from the aforesaid region and presents the tobacco to a front picker roll 56a which is secured to and rotates with a rotating shaft 56. Associated with the picker roll 56a is a dust roller 57a mounted on shaft 57. The picker roll 56 deflects the tobacco downwardly into a filler chute 58 which guides the tobacco downwardly onto a feeder belt 59, disposed in a U-shaped feeder trough 61 located at the lower end of the filler chute 58. i

The above description of the operation of the feeder is brief since it is a well-known apparatus and the apparatus of the invention relates only to the interrelationship between the mechanism for driving the various ele ments of the-feeder and does not affect the basic operation of the feeder elements or their relative functions.

Referring now to Figure 2 of the present invention, the drive mechanism illustrated for the feeder discussed in Figure 1, is identical to the prior art apparatus except that in accordance with the present invention an idler gear 75 illustrated with brokenlines is removed and all the elements on-the selected pin or picker roller shaft 53 or 56 to the right of a gear 76, which originally mated with the gear 75, have been added in order to accomplish the objects of the present invention as have all the elements which are physically related to the elements to the right of the gear 76. In both the prior art control apparatus and the present apparatus a control impulse motor 77 is adapted to control the position of a shaft 78 having secured thereto a drive gear 79. The drive gear 79 is coupled via an endless chain 31 to the variable speed control mechanism specifically illustrated as a variable speed cone pull y, and generally designated by the reference numeral 82. Substantially constant speed rotational energy is applied to the cone pulley 82 from a source of rotary power (not illustrated) via an endless drive chain 83 which engages around sprocket 83a and constitutes the input or drive part of the adjustable speedcone pulley mechanism 82.. The cone pulley 82 drives an output endless belt 84 the speed of which 'is determined first of all by the linear 'speed'of the endless belt Y33 and secondarily and controllably byzthe position of the shaft 78 working through the chain 81. The endless belt 84 drives a main drive pulley 86 which in turn drives an input shaft 8 7 to the feeder, the pulley 86 being mounted on the shaft 87. The shaft 87 carries a first drive gear 88 which is suitably coupled to the cleaner shaft 7 in order to provide rotary motion for this shaft. The shaft 87 also drives a gear 89 which engages the outer periphery of a larger gear 91 having secured to and rotatable therewith a smaller gear 92. The smaller gear 92 drives a further gear 93 having secured thereto and rotatable therewith a smaller gear 94. The gear 94 drives a larger gear 96 having secured thereto and rotatable therewith two small gears 97 and 98. The gear 97 drives a large gear 99 which is secured to and adapted to rotate the shaft 18 of the main drum 17 while the gear 98 drives an endless chain 101 adapted to drive a number of other gears as subsequently related.

The gears 91 through 99 constitutes a speed reduction mechanism for obtaining the proper velocity for the main drum shaft 18 and other elements of the system. The main drum shaft 18 extends through the feeder and has secured to the opposite end thereof a drive pulley 102 for driving an endless chain belt 103. The belt is looped about a drive gear 104 secured to and rotatable with the rear drum shaft 14 on which is supported the rear drum 13. The endless chain 103 is also adapted to pass over a gear 106.

Returning again to the reduction gear mechanism 91 through 99 the gear 9394 is mounted on and rotates a shaft 107 which extends through the feeder assembly and has secured thereto on the opposite side of the feeder assembly a sprocket 108, an eccentric 109 and a further sprocket 111 arranged serially along the shaft. The eccentric 109 drives a push-rod 112 which has secured to one end thereof a pawl mechanism 113 for driving a drive ratchet 114 secured to the top drum shaft 33 to which is secured the top drum 32. The sprocket 111 drives an endless chain 116 which is looped about a sprocket 117 and maintained taut by idler sprockets 113 and 11851. The sprocket 117 drives a shaft 119 on which is secured an eccentric (not illustrated) which vertically reciprocates the end 31 of arm 28 (see Figure 1) and thereby reciprocating the tamper 24. The sprocket 108 drives an endless chain 120 which is looped about a further sprocket 121 mounted on the steel drum shaft '45 to which is secured the steel drum 47.

Returning now the endless chain 101 which is driven by the drive sprocket 98, the chain passes partially around over sprocket 122, under and partially around a sprocket 123, over and around sprocket 124, and under a sprocket 126, and over a further sprocket 127 The sprocket 126 is secured to the front dust roller shaft 57.

In accordance with the'prior art feeder mechanism and control therefor, the gear 75 coupled the gear 76 on the pin roller shaft 53 to the gear 127 and as a result all elements of the feeder mechanism were coupled to be driven at a predetermined speed with respect to the input shaft 87 Thus, when a change in weight or density of the mass of tobacco fed to the rod forming portion of the cigarette-making machine changed and the change was suflicient to produce a control function, the motor 77 repositioned the shaft 78 so that the speed of rotation of the belt 84 to the drive pulley 86 was changed in order to correct the speed of the entire feeder mechanism. In such a system it is apparent that several delays are" inherent in the control mechanism due primarily to two factors. The first of these factors is the inertia of the feeder mechanism. The feeder utilized in the con ventional tobacco-making machine with which the present invention is concerned is 44 inches in length and it can be readily seen that the mechanical inertia of the large number of drums and rollers and gears involved in a feeder of such a size is quite considerable. The second factor contributing to the slow response of the system to a signal indicative of deviation of the weight of tobacco from a desired value is the transportation lag between theapparatuswhich corrects the variation in weight and the apparatus which detects this variation. In the apparatus illustrated and utilized in the prior art the point at which major changes in the amount of tobacco being fed could be considered as taking place at the intersection at the top drum 32 and the main drum 17. The tobacco then proceeded through the remainder of the feeder, dropped onto the moving belt 59 in the filler trough 61 and then proceeded into the tobacco rod forming mechanism where subsequently the weight is measured by a suitable detector such as a beta ray gauge. It can be seen therefore that a considerable length of time elapsed between the detection of a variation in the weight of the tobacco and the time at which the corrected weight arrived at the detector. First, the inertia of the feeder mechanismhad to be overcome to eifect the correction and then the tobacco which is fed at the new rate must proceed through the mechanism and to the point at which the detector is located.

In accordance with the present invention the transportation lag and the mechanical inertia of the system are both considerably reduced by removing the gear 75 from the system and independently controlling the speed of rotation of the pin roller and/ or picker roller shafts 53 or 56, respectively while, electrically controlling the speed of the remainder of the system in accordance with the speed of the selected roller shaft.

Specifically, the selected roller shaft 53 or 56 is extended past the gear 7 6 and has received to the extension a gear 128 which is indicated in Fig. 2 as mounted on pin roller shaft 53, but as previously described it may if desired be mounted on picker roll 56. Gear 128 meshes with a second gear 129 driven from a new control gear reduction unit 131. The input to the gear reduction 131 is from a shaft 132 having a gear 133 mounted on the one end thereof, which gear is driven through the intermediary of an endless chain 134 by means of a sprocket 136. The sprocket 136 is mounted on an output shaft 137 of a variable speed drive unit 138. The variable speed unit 138 is driven by a substantially constant speed shaft 139 and the output speed of the shaft 137, relative to the speed of the shaft 139, is controlled by the position of a speed control shaft 141. The position of the shaft 141 is controlled by a control impulse motor 142 coupled to the shaft 141 via gear 143 i a motor shaft 144 and gear 145 on the shaft 141. The

gear 143 is also coupled to a gear 146 which is connected to a shaft 147 of an electrical potentiometer 148. One additional change is made in the prior art mechanism and this is the coupling of an input shaft 149 of a potentiometer 151 to the original weight change shaft 78.

Proceeding now to the description of the operation of the novel apparatus of the present invention, the position of the motor 142 is controlled by a weight detector and is rotated in one direction or the other depending upon whether the weight is greater or less than the desired standard weight. Upon rotation of the motor 142 the control shaft 141 of the variable speed drive 138 is rotated so as to increase or decrease the speed of rotation of the shaft 137 depending upon whether the weight was less or more than the desired weight. The shaft 137, as previously indicated, determines the speed of the selected roller shaft via the gear reduction box 131 and other appropriate gears. The pin or picker roller shafts in a conventional machine rotate at approximately six revolutions per minute and it has been found that the deviations in the speed of the shaft in this apparatus must not occur too rapidly. In one example of the system provided in accordance with the present invention, the gear reduction ratio of the speed reducer 131 is fifty-to one while the speed of rotation of the shaft 139 is approximately 283 revolutions per minute. The speed of the shaft 139 and the ratio of the gear reducing mechanism 131 are related to the extent that with a specific a 9* a gearr'atio producing the desired speed of rotation of the selected roller shaft 53 or 56, the speed of the shaft 139 should be such that the shaft 141 is positioned approximately half-way between the two extremes of control. The gear reduction ratio of the mechanism 131 is chosen as large as it is so that changes in speed of the output shaft 137 produce slow changes in speed of the selected roller, that is, the rate of change in speed of the shaft is not too great. This is an important fact since it has been found that extremely poor regulation is obtained if the rate of change of speed of either shaft is too great.

It will be noted that the motor 142 not only controls the position of the shaft 141 but also controls the position of the input shaft 147 of the potentiometer 148. The gears .143, 1 45 and 146, it will be noted, constitute a fixed ratio gear mechanism which produces a fixed correspondence between rotation of the shafts 141, 144 and 147. As willbe indicated more fully upon discussion of the circuit of Figure 3, the potentiometer 148 and the potentiometer 151 which is controlled by the shaft 78 are connected in circuit such that upon a deviation of the potentiometer 148 from a prior setting the motor 77 is energized to vary the output speed of the cone pulley 82 by an amount determined by the amount of variation of the potentiometer 148. The change of position of the motor 77 thus changes the speed of rotation of the remainder of the feeder mechanism and in consequence the entire mechanism is controlled by the weight detector via the motor 142. However, it is apparent that the mechanism which is directly responsive to the weight detector, that is, the mechanism for controlling the speed of rotation of the selected roller shaft has a substantially smaller physical inertia than the remainder of the drive mechanism and therefore its speed of response is considerably greater than the remainder of this mechanism.

' This is permissible in accordance with the present invention since the control has been applied to the selected roller shaft astillustrated, or as indicated previously, may be applied to a picker roller shaft, since both the pin roller and the second picker roller operate at a point where a reservoir of tobacco, is provided of such quantity that even a relatively large increase in the speed of rotation of the pin roller does not exhaust this reservoir before the mechanical inertia of the remainder of the feeder mech 'anism has been overcome and achieve a new speed as determined by the position of the motor 142. Thus, although the inertia of the overall feeder system has not been decreased the speed of response of the control function is materially increased and in addition it occursat a point which is substantially closer to the detectorthan the original control point taken at the point of approximate tangency at the top drum and the main drum. The overall result of the system then is to reduce both the mechanical inertia and the transportation lag of thesystem and therefore provide a relatively short term control for the tobacco-making machine as compared with the control interval in the prior art control systems.

The circuiting for controlling the position of the motor 142 in response to a signal derived from a Weight detector, and the position of the motor 77 in response to the position of the motor 142 is illustrated in Figure 3 of the accompanying drawings and reference is now had to this figure. As previously indicated a suitabledetector which may be a capacitive weight gauge or a beta-ray weight gauge may be utilized to produce an electrical signal indicative of the weight of the tobacco in the cigarette making machine and in Figure 3 the detector is generally designated by the reference numeral 160. The output signals from the detector 160 are applied toa suitable amplifier 1'61 and thence to a :motor control circuit 162. The motor control circuit 162 is connected via three leads 1'63, 164 and 166 to three input terminals of the control .impulse'motor 142. The motor control circuit applies a voltage between the leads 1'63 and 164 in order to produce rotation of the motor 142 in one direction and apshaft tends to reduce the error.

'is controlled by a solenoid 216.

. a 10 v pliesa voltage between the leads 164 and 166 if it is de sired to produce rotation of the motor 142 in the opposite direction.

Upon deviation of the weight of the tobacco, being measured, from a desired weight, the motor control circuit 162 energizes the motor 142 in order to produce a rotation which through its control on the selected roller Specifically, the motor 142, and reference is now made to Figure 2, varies the speed of the selected roller shaft to vary the rate at which the tobacco is picked up by the selected roller and showered onto the feeder belt. Simultaneously, and reference is now made to Figure 3, the motor 142 via a mechanical linkage 167 varies the position of a slider 168 on a resistance 1-69 forming one side of a Wheatstone bridge circuit 171. The other side of a Wheatstone bridge circuit 171 comprises a resistance 172 having a slider 173 associated therewith. The resistances 169 and 172 are connected in parallel and a sourceof DC. voltage 174 is applied across the parallel connected resistors. The slider 173 is mechanically coupled via a linkage 176 to the variable position motor 77 and as will now become apparent during subsequent discussion, when rotation of the motor 142 produces unbalance of the bridge 171 due to movement of the arm 168, the motor 77 is energized to rebalance the bridge via its connection to the slider 173 of the resistor '172. The members 172 and 173, and members 168 and 169 are shown in Fig. 2. as potentiometers 151 and 148, respectively. The members 176 and 167 are identified in Fig. 2 as members 149 and 147, respectively. 'Rotation of the motor 77 also changes the speed of the remainder of the feeder mechanism to insure that a sufficient quantity of tobacco is supplied to the aforesaid reservoir from which the pin roller withdraws tobacco.

The slider 168 of the resistance 169 is electrically coupled via a lead 177 to a terminal 178 of a differential relay 179, having two coils 181 and 182 connected in series between the terminal 178 and a second terminal 183. The coils 181 and 182 of-the differential relay 179 are connected in series across the detector circuit of the Wheatstone bridge 171 and upon unbalance of the bridge, deflect a meter pointer contact 193 of the meter relay 179 into contact with a first control terminal 194 or in the opposite direction depending upon the sense of unbalance of the bridge into contact with a second control terminal 196; the needle 193 being connected to a junction of two leads 197 and 198. The arrangement for connecting the coils 181 and 182 across the bridge constitutes a series circuit including a lead 184 and a normally closed pair of contacts 186 of a first timing mechanism 187 to a lead 188. The lead 188 is connected via a pair of normally closed contacts 186' of a second timing mechanism 187 to a lead 192 which. is connected electrically to the slider 173 associated with the resistance 172. The structure of the mechanism 187 is identical to that of the timing mechanism 187 and corresponding parts in the former mechanism carry the same numbers with primes of the parts in the latter mechanism. The timing mechanism 187 which may be of the type described in Anderson Patent No. 2,175,864 and Patent No. 2,175,865, comprises a synchronous motor 201 connected across a pair of leads 282 and 283 adapted to be connected to a suitable source of alternating current. The synchronous motor 281 drives an output shaft 204 which is coupled via an electromagnetically-actuated clutch 206 to a shaft 207 having arranged thereon three timing cams 208, 209 and 211. Each of the timing cams is adapted to control a distinct pair of contacts, the cam 268 controlling a pair of contacts 212, the cam 209 controlling a pair of contacts 213 and the cam 211 controlling the aforesaid contact 186. The electromagnetically-actuated clutch 206 is shifted into and out of engagement by a shifting fork 214 the position of which The solenoid 216 is 11 connected in series with the contacts 212 across the A. C. leads 202 and 203 while the contacts 212 are adapted to be shunted by the meter relay needle 193 and terminal 194 connected across the contacts 212 bym'eans of leads 197 and 217.

The cam actuated contacts 213 are connected in series between first input terminal 218 of the motor 77 and the A.C. lead 202 while a second input terminal 219 of the motor 77 is connected to the lead 203. Thus, when the contacts 213 are closed the control impulse motor '77 is energized to rotate in a first direction. A third input terminal 221 of the motor 77 is connected via a lead 222 to a pair of normally open contacts 213 of the second timing mechanism 187'.

In the apparatus 187 the continuously rotating synchronous motor 201 is connected via a lead 223 to the A.C. lead 203 and via a lead 224 to the A.C. lead 202. The contacts 212 are connected via leads 198 and 227 to the meter needle contact 193 and the second meter stationary contact 196, respectively. Therefore, when the needle 193 is closed against contact 196 the meter relay shunts the contacts 212 which are connected in series with the contacts 212' across the AC. leads 223 and 224.

In operation, the relays 216 and 216' are deenergized and therefore the shafts 207 and 207 are stationary. Upon movement of the slider 168 by the motor 142 by a predetermined amount, the meter relay 179 is sufficiently energized to close the needle contact 193 against one of the contacts 194 and 196 and for the purposes of explanation it is taken to be the contact 194. In consequence the contacts 212 are shunted and the relay 216 is energized to cause the clutch fork 214 to'move in a forward direction thus engaging the clutch 206. The motor 201 is constantly rotating and therefore as soon as the clutch 206 is engaged, the shaft 207 is rotated. The cam 203 immediately closes the contacts 212 and provides a holding circuit for the relay 216, while at the same time the contacts 186 which are in series with the meter relay windings 181 and 182 is broken so that the needle 193 returns to the zero position. There- 'fore, the contacts 2 12 provide the only means for maintaining the relay 216 energized and therefore the clutch 206 in a coupled condition. Rotation of the shaft 207 also produces rotation of the cam 209 which depending upon the contour of its surface closes the contacts 213 for a predetermined interval to connect thereby the control impulses motor 77 across the leads 202 and 203. During this predetermined interval the motor moves the arm 173' a definite distance along the resistance 172 in such a direction as to tend to rebalance the bridge 171. At the end of one revolution of the shaft 207 the contacts 212 are opened immediately prior to reclosing of contacts 186 so that when contacts 212 are separated the solenoid 216 is deenergized and the clutch 206 is decoupled. Therefore, the holding contacts 212 restrict the motor 77 to precisely one revolution of the shaft 207 for each closing of the contacts of the meter relay 179. If complete rebalancing of the system has not been eflected by the motor 77 during one revolution, the meter relay 179 is again energized upon closing at contacts 186 and causes its contacts to close to institute a second cycle of operation of the timing mechanism 187 during which the motor 77 is again energized to change the speed of the feeder mechanism and to attempt to rebalance the bridge 171. This cycle of events continuous until the bridge 171 has been rebalanced to a point where the moving contact 193 is no longer deflected sufiiciently :to engage contact 194. It is preferable that the cam 209 be contoured so as to produce energization of the motor 77 for an interval which produces rebalancing of the bridge 171 during one cycle of operation when the bridge is unbalanced as a result of normal or expected varia- :tions with time in the quantity of tobacco supplied by the feeder.

This time interval is variable between the machines and in this respect the timing must beadjusted when the ap'paratusis initially installed on a particular machine.

The operation'of the circuit has been described for ane'rror in the bridge 171 which causes the meter 179 to close its contact 193 against the contact 194. In;the event that the unbalance of the bridge 171 is 'suchjthat the-meter 193 is closed against the cohtact196 the mechanism 187 is energized and the A.C. voltage across the leads 202 and 203 is applied between'the terminals 219 and 221 of the control impulse motor 77 to rotate it in a direction opposite to that produced when "the mechanism 187 is energized. Other than this the operation of the circuit is identical regardless of which direction the needle 193 of the relay 179 is deflected. v

It is not intended to limit the apparatus'of the invintion to utilization of a specific motor control circ it; the circuit illustrated in Figure 3 being merely one type of suitable circuit. Another system in which the apparatus of the invention may be employed .is described in copending application Serial No. 749,120, filed July 17, 195 8, in the names of Harris, Lloyd and Updike, Jr., and assigned to Philip Morris'ln corporated. V

The apparatus of the present invention has been described as applicable to the control of the tobacco feeding mechanism. Althoughthe apparatus is particularly adapted to such a use, it may be of more general applicability and specifically may be applied to various anisms where high and low inertia feed mechanisms respectively withdraw material from and supply material to a reservoir situated between the two inertia systems.

While we have described and illustrated one specific embodiment of our invention, it will be clear that variations of the general arrangement and of the details of construction which are specifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims. A I I Having thus described the invention, what is claimed 1. A mechanism for feeding comminuted material comprising a reservoir for comminuted material, a relatively high inertia feeding mechanism for feeding corr minuted material to said reservoir, a relatively low inertia feeding mechanism for withdrawing comminuted material from said reservoir and supplying it to a utilization mechanism, detector means responsive to the quantity being so supplied for controlling the speed of operation of said low inertia mechanism so as to maintain the rate at which it feeds said material to said utilization mechanism substantially constant, and electrical sensing and control means for controlling the speed of said high inertia feeding mechanism inaccordance with the speed of said low inertia mechanism, said reservoir having a capacity such that the quantity of material therein is maintained within predetermined limits during the interval required for said high inertia mechanism to attain a feed rate equal to the withdrawal rate of said low inertia mechanism upon a change in the withdrawal rate as dictated by said detector means.

2. A mechanism for feeding shredded material comprising a reservoir for shredded material, a relatively high inertia feeding mechanism for feeding shredded material to said reservoir, a relatively low inertia feed ing mechanism for withdrawing shredded material from said reservoir and supplying it to a utilization mechanism, detector means responsive to the quantity being so supplied for controlling the speed of operation of said low inertia mechanism so as to maintain the rate at which it feeds said material to said utilizationmechanism substantially constant, and electrical sensing and control means for controlling the speed of said high inertia feeding mechanism in accordance with the speed of said low inertia mechanism, said reservoir having a capacity such that the quantity of material therein is maintained within predetermined limits during the interval required for said high inertia mechanism 'to attain a feed rate equal to the withdrawal rate of said low inertia mechanism upon a change in the withdrawal rate as dictated by said detector means.

3. The combination in accordance with claim 2, wherein said electrical sensing and control means comprises means for producing a signal indicative of a difference between desired rates of input into and withdrawal of material from said reservoir and means for controlling the speed of said high inertia mechanism in accordance With said signal.

4. The combination in accordance with claim 2, wherein said shredded material is tobacoo filler for cigarettes.

S. The combination in accordance with claim 4, wherein said low inertia member comprises a pin roller of a tobacco feeder.

6. The combination in accordance with claim 4, wherein said low inertia mechanism comprises a forward picker roller of a tobacco feeder.

7. The combination in accordance with claim 4, wherein said high inertia mechanism comprises a rear drum, a main drum, atop drum and a front steel drum of a tobacco feeder.

8. The combination in accordance with claim 4, wherein said reservoir comprises a front steel drum and a vibrating collator plate disposed adjacent the surface of said front steel drum.

9. The combination in accordance with claim 4, wherein said detector means comprises measuring means for procuring an electrical signal indicative of the weight of material supplied by said low inertia feed mechanism and motor control means for controlling the speed of said low inertia feed mechanism in accordance with the signal produced by said measuring means.

10. The combination in accordance with claim 2, wherein said mechanism for feeding shredded material comprises a feeder for feeding shredded tobacco to a cigarette making machine, and wherein said high inertia mechanism comprises a first shaft, a rear drum, a main drum, a top drum and a front steeldrum, coacting when rotated to supply tobacco to said reservoir and means for rotating all of said drums from a first shaft.

11. The combination in accordance with claim 10,

wherein said reservoir comprises a vibrating collator plate disposed adjacent said front steel drum, said high inertia mechanism feeding tobacco between said collator plate and said front steel drum.

12. The combination in accordance with claim 11, wherein said low inertia mechanism comprises a rotating pin roller for withdrawing tobacco from between said collator plate and said front steel drum.

13. The combination in accordance with claim 12, wherein said detecting means comprises means for measuring the weight of tobacco supplied by said pin roller and means for developing an electric signal proportional thereto, a variable drive mechanism having a variable speed output shaft, and a variable-position, speed control shaft, means for coupling said output shaft to rotate said pin roller, and a variable position motor for positioning said speed control shaft in accordance with signals produced by said means for measuring.

14. The combination in accordance with claim 13, wherein said electrical sensing and control means comprises a second variable speed drive mechanism having a variable-position, speed control shaft and a variable speed output shaft coupled to said first shaft, a second variable position motor for positioning said control shaft of said second variable speed drive mechanism and electric means for positioning said second variable position motor in accordance with the position of said first variable position motor.

15. The combination in accordance with claim 14, wherein said electric means comprises a Wheatstone bridge circuit having a plurality of variable resistances, I

means for varying one of said resistances to unbalance said bridge upon movement of said first variable position motors and means for coupling another of said variable resistances to be varied by said second variable position motor, and motor control means responsive to unbalancing of said bridge means for rotating said second variable position motor to rebalance said bridge means. 16. The combination in accordance with claim 15, wherein said motor control means comprises means for repetitively rotating said second variable position motor for predetermined intervals of time until said bridge is rebalanced.

No references cited. 

